Fix @nospecialize with zero args

Author: mlechu

src/compat.jl

@@ -82,7 +82,7 @@ end
 
 """
 Return `e.args`, but with any parameters in SyntaxTree (flattened, source) order.
-Parameters are expected to be as `e.args[pos]`.
+Parameters are expected to be at `e.args[pos]`.
 
 e.g. orderings of (a,b,c;d;e;f):
   Expr:       (tuple (parameters (parameters (parameters f) e) d) a b c)
@@ -461,11 +461,13 @@ function _insert_convert_expr(@nospecialize(e), graph::SyntaxGraph, src::SourceA
         elseif nargs === 0
             # pass
         elseif e.args[1] === :nospecialize
-            if nargs > 2
+            if nargs === 1
+                child_exprs[1] = Expr(:quoted_symbol, :nospecialize)
+            elseif nargs > 2
                 st_k = K"block"
                 # Kick the can down the road (should only be simple atoms?)
                 child_exprs = map(c->Expr(:meta, :nospecialize, c), child_exprs[2:end])
-            else
+            elseif nargs === 2
                 st_id, src = _insert_convert_expr(e.args[2], graph, src)
                 setmeta!(SyntaxTree(graph, st_id); nospecialize=true)
                 return st_id, src

test/macros_ir.jl

@@ -186,3 +186,25 @@ cmdmac`hello`
 cmdmac`hello`12345
 #---------------------
 1   (return "hello from cmdmac with suffix 12345")
+
+########################################
+# @nospecialize (zero args)
+function foo()
+    @nospecialize
+end
+#---------------------
+1   (method TestMod.foo)
+2   latestworld
+3   TestMod.foo
+4   (call core.Typeof %₃)
+5   (call core.svec %₄)
+6   (call core.svec)
+7   SourceLocation::1:10
+8   (call core.svec %₅ %₆ %₇)
+9   --- method core.nothing %₈
+    slots: [slot₁/#self#(!read)]
+    1   (meta :nospecialize)
+    2   (return core.nothing)
+10  latestworld
+11  TestMod.foo
+12  (return %₁₁)

test/utils.jl

@@ -112,7 +112,10 @@ function uncomment_description(desc)
 end
 
 function comment_description(desc)
-    replace(desc, r"^"m=>"# ")
+    lines = replace(split(desc, '\n')) do line
+        strip("# " * line)
+    end
+    join(lines, '\n')
 end
 
 function match_ir_test_case(case_str)
@@ -228,7 +231,7 @@ function refresh_ir_test_cases(filename, pattern=nothing)
         else
             ir = case.output
         end
-        println(io,
+        (case == cases[end] ? print : println)(io,
             """
             ########################################
             $(comment_description(case.description))